In industries related to radio waves, a development of systems using TVWS (TV White Space: white space for television) is being advanced. In order to realize a communication using the TVWS, there is a need to modify existing wireless communication systems, and to make operations of these systems to be conformed to laws and regulations related to radio waves.
As a condition required in the system using the TVWS, there can be cited, for example, a possession of function of selecting a frequency (band) which does not overlap with a frequency band used by a wireless station (TV, in this case) having a high priority with which the TVWS is used (or a frequency band which is assigned to the wireless station). This is for avoiding an interference of communication of the wireless station which is licensed and has a high priority in terms of radio wave regulating.
In order to realize the function as above, one option to be required is to prepare a database recording a state of using radio waves in the TVWS, particularly, a state of assignment of radio waves in a wireless station of TV and the like with high priority (frequency database). Normally, the frequency database is created by an authority of radio wave regulating, and is provided to the public. The frequency database manages, regarding a predetermined frequency band of TV and the like, an ID of licensed wireless station (broadcast station), a frequency (band) assigned to the wireless station, positional information of the wireless station and the like, and the positional information of the wireless station is often represented as position coordinates formed of latitude, longitude and the like. When the system using the TVWS selects a frequency to be used, it is possible to previously avoid the frequency (band) licensed to the wireless station with high priority by accessing the frequency database as above.
In order to judge the presence/absence of the wireless station with high priority (or the presence/absence of possibility of giving an interference to the wireless station) by utilizing the frequency database, there is a need to know a positional relationship between the wireless station and a system that uses the TVWS. However, as the system that uses the TVWS, a low power system which is not required to be licensed is assumed, so that there is a problem that it is difficult to know the positional relationship in advance.